Conventionally, there has been known a power source apparatus provided with a bus bar module (see JP 2014-238986 A). To be more specific, as shown in FIG. 14, this power source apparatus includes a battery assembly 602 which is formed by disposing a plurality of prismatic batteries 601 in a row, and a bus bar module 610 mounted on an upper surface of the battery assembly 602.
Each of the plurality of batteries 601 has a positive electrode 603 and a negative electrode 604 on both ends of an upper surface in a width direction. In the battery assembly 602, the positive electrodes 603 and the negative electrodes 604 are disposed in two rows in a stacking direction of the batteries 601 (hereinafter, referred to as “first direction”) such that the positive electrode 603 and the negative electrode 604 are disposed alternately on a straight line.
The bus bar module 610 includes: a plurality of bus bars 611 which connect the plurality of batteries 601 in series by connecting the positive electrode 603 and the negative electrode 604 of the batteries 601 disposed adjacently to each other; and a case 613 which houses the plurality of bus bars 611. In each of the plurality of bus bars 611, a pair of through holes 612 into which the positive electrode 603 and the negative electrode 604 which are electrodes disposed adjacently to each other are inserted is formed in a plate-like metal. The case 613 is formed into an approximately rectangular shape substantially equal to a shape of the upper surface of the battery assembly 602. The case 613 is made to overlap with the upper surface of the battery assembly 602. A plurality of bus bar housing portions 614 are disposed on a straight line on edge portions of the case 613 in a width direction. That is, the plurality of bus bar housing portions 614 are disposed in two rows spaced apart from each other in a width direction of the bus bar module 610 in the case 613.
In the bus bar module 610 having the above-mentioned configuration, the positive electrodes 603 and the negative electrodes 604 of the batteries 601 are inserted into the through holes 612 formed in the bus bars 611, and nuts 605 are threadedly engaged with the positive electrodes 603 and the negative electrodes 604 so that the bus bar module 610 is mounted on the upper surface of the battery assembly 602.
However, in the power source apparatus 600, the bus bar module 610 is fixed to the battery assembly 602 only at both end portions in the width direction (that is, not fixed at a center portion in the width direction). Accordingly, variations in size at respective positions (to be more specific, variations in height at the respective positions in the first direction) are generated so that there may be a case where it is difficult to insert the power source apparatus 600 into an installation space at the time of installing the power source apparatus 600.